1,721,035 research outputs found
Monitoring, modelling and mitigation of earth slides-earth flows in the northern Apennines
No full textThe article show some experiences about slow moving landslides monitoring and modelling, which are located in northern Appennines
2014-2015 Tritium values in small and shallow aquifers in northern Apennines
No full textTritium data relating to actual rainfall in north of Italy and in particular in the northern Apennines are rare or missing. The reasons of this lack of data frequently depends on the high cost of analysis and the necessity of high amount of water to perform the analysis itself. In order to obtain these data a valid alternative can be analyze the amount of Tritium in unconfined, shallow and small aquifer not affect by human activities (such as sewage).
Recent studies, applied to the hydrogeology of the Po plain or of the Apennine slopes, highlight, in rainfall water recharging shallow aquifer, tritium values ranging between 6 T.U. and 12 T.U., higher than those detected in other and different areas of Italy or of the South Europe.
The aim of this paper is to highlight first results of tritium analyses performed on spring draining shallow aquifers in northern Apennines, characterized by the absence of human activities. The peculiarity of sampling point (spring are characterized by small and well defined catchment areas as well small differences between the infiltration/recharge elevation and the spring elevation) makes results representative of mean tritium value of rainfall recharge in the studied area.
In detail, during 2014-2015 three springs located at different elevation in Secchia Valley have been sampled and analyzed. Tritium analyses performed on a total of 5 samples highlight the following results: the maximum value
(5.0±0.7 T.U.) is detected in water collected in November whereas the minimum value ( 3.7±0.6 T.U.) is obtained in May. Therefore a mean annual value of 4.2±0.7 T.U. in the studied area have been highlighted
Slope dynamics and streambed uplift during the Pergalla landslide reactivation in March 2016 and discussion of concurrent causes (Northern Apennines, Italy)
No full textOn March 28, 2016, the toe zone of the apparently dormant Pergalla earthslide-earthflow (Northern Apennines, Italy) had a paroxysmal reactivation. In the course of 2 days, displacements up to almost 8 m severely damaged several houses and roads. At the bottom of the slope, the emersion of rotational sliding surfaces determined the uplift of almost 3 m of the Nure river streambed that was consequently partially dammed. The paper describes the landslide event on the basis of field surveys and analysis of post-event aerial photos, as well as data from geophysical surveys and pre- to post-failure displacement monitoring. It also discusses the possible concurrent causes of the event, including antecedent rainfall, the migration of active streambed channels of Nure river toward the landslide toe in the previous year, and the existence of long-term pre-failure slow movements. It is concluded that these factors, together with the presence of sliding surfaces extending beneath the valley floor, should be primarily considered if a preventive assessment of river damming potential due to streambed uplift should be made for other similar landslides in the Apennines
Integrated displacement and activity analysis at the Valoria landslide (Italian Apennines) through automated topographic monitoring, image correlation velocimetry and surface roughness computation
No full textISBN 2-95183317-1-5At the Valoria landslide located in the Italian Apennines, surface monitoring data acquired by an automated total station were analyzed. The system provided short-term information on the behavior of the material during crisis and the duration of reactivations. Long-term displacements and morphometric properties were studied using a geographic information system (GIS). Results from monitoring show a strong correlation between rainfall related triggering of mass wasting in the crown zone and subsequent downslope reactiva-tions. We found that crown-to-toe zone reactivations generally occur within only 6 weeks. Further findings indicate that earth slide materials in the head zone fail almost instantaneous conversely to earth flow materials in the track channel. The findings are complemented by a digital image correlation analysis of multi temporal, high-resolution digital elevation models (DEM) acquired in 2006, 2007 and 2009. We utilized this technique to compute velocities and displacements of pixels in the DEMs between 2006 and 2009. It was found that both azimuth and magnitude of displacements could be reconstructed in for the crown zone, the main track channel and the landslide toe. The results from the image correlation compare well to displacements obtained from independent monitoring methods (GPS and interpreting of shaded reliefs maps). Based on the assump-tion that increased materials movements result in higher terrain roughness, we used LiDAR-derived to per-form a raster based roughness analysis. Different roughness calculation methods were applied to 0.5 m eleva-tion grids using different Kernel sizes. The performance of a supervised and an unsupervised approach was evaluated. Findings from the supervised approach showed that the difference between active and dormant landslides is evident in some cases but also that earth flows and dormant landslides tend to have a similar roughness patterns as stable areas. Results from the unsupervised approach demonstrated that landslide roughness is heterogeneous and that non-landslide areas may have a similar morphometric signature. In this study it was demonstrated that near- and remote sensing techniques are crucial, as well as complimentary in the analysis of landslide hazard. Applying both approaches can yield a more complete picture of the defor-mation history of landslide
Modellazione numerica dei meccanismi di riattivazione di grandi frane per scivolamento di terra: l’esempio della frana di Tolara, Appennino settentrionale
No full textThe time and space evolution of large earth slides in weak and complex rockmasses, that characterize thenorthern Apennines, is depending on geological setting and past climate. At the present the reactivation of theselandslides are due to mainly to hydrogeological and geotechnical features. This paper describes the hydrogeological andgeotechnical features of these landslides and the reactivations mechanism using coupled 2D hydrogeological numericalmodel and limit equilibrium analysis (Geoslope, 2004). The case study is the Tolara landslide (Modena Apennines) thatresumed activity in 2002. In this landslide some hydrogeological and geotechnical data have been collected from 2003 todate
Hydro-mechanical features of landslide reactivation in weak clayey rocks
No full textIn the northern Apennines, four representativelarge and deep seated landslides affecting weak rockmasses have been studied before, during and after reactivationevents. Semi-continuous and continuous monitoringin the 2004–2006 period included the dormancy, reactivationand suspension phases, allowing some comments tobe put forward as regards the hydro-mechanical conditionsthat drive the reactivations. The data have highlighted theinteractions between groundwater and displacement ratesin different sections of the slope
Hydrogeological investigation of Pietra di Bismantova slab and surrounding slope deposits (northern Apennines, Italy)
No full textThe recent application of hydrochemistry to unstable slopes reveals the contribution of this technique to better understand hydrological processes, water rock interaction and to outline groundwater flow paths. The aim of this short note is to present results from two years of semi-continuous monitoring (discharge, EC, temperature) of two springs (Eremo and F. Cornia spring) flowing along the SE slope of Bismantova fractured slab, in the stable and unstable portion of the slope respectively. Both springs follow the precipitation pattern with the increase of discharge and decrease of temperature as consequence of rainfall recharge; moreover the increase of EC seems to suggest interaction beetween groundwater and mineral phases hosted along fractures of the slab. Using chemical results a first inverse modeling with PHREEQC have been performed in order to identify the interaction between water infiltrating in host-rock and mineral phases, as well to reconstruct geochemical evolution of groundwater from the upward stable portion to the downward unstable portion of the slope
Evidence of deep-water inflow in a tectonic window of the northern Apennines (Italy)
No full textWater samples from the river network and from some shallow and brackish springs located in a tectonic window of the northern Apennines of Italy were studied in the frame of a comprehensive hydrogeological investigation in order to better understand the origin and the mixing processes between the two water types noticed also in previous studies (Ca–HCO3 and Na–Cl). A sampling campaign covering the drought period during year 2010 was planned to gather electric conductivity, temperature and redox potential data along the river network and on groundwater occurrences located inside the tectonic structure. Additionally, eight water samples were collected for hydrochemical (major anions and cations: Na+, K+, Ca2+, Mg2+, HCO3 −, Cl−, SO4 2− and trace ion Btot) and isotopic (δ18O, δ2H, 3H) analyses and compared with other eighteen samples from shallow and brackish springs collected near the study site during the period 2005–2012. Moreover, river discharge and water balance estimations were carried out. Results confirmed the presence of old Na–Cl water with salinity progressively increasing up to 5.5 g l−1 at the northern termination of the tectonic window. These values are in agreement with the ions contents of the most mineralized spring (Macognano spring: salinity of 7.6 g l−1), which has been considered as having the deepest and longest flow-path. Stable isotopes and trace ions contents are consistent with rainfall and snowmelt water mixed with brines associated with a hydrocarbon reservoir hosted at depth. Considering as end-member the more mineralized Na–Cl water, a cumulate inflow in the range of 12.9 ± 5.9 l s−1 has been estimated. This aliquot is released into the river network with different mixing proportions by the groundwater occurrences discharging from the autochthonous flysch unit
Forward simulation of groundwater level changes induced by deep drainage wells in Succiso earth slide (northern Apennines, Italy)
No full textThe Succiso landslide is a large scale active earth slide located in the northern Apennines of Italy, in the upper Enza river basin (Province of Reggio Emilia, Emilia Romagna
Region). It extends from 1075 to 800 m a.s.l., affecting an area of about 0.5 km2 for a length of about 1.6 km and a maximum width of 500 m. The landslide area is characterized by flysch and claystone bedrock, by glacial and landslide deposits of various type and by more than 2000 mm rainfall per year. The landslide is named after the village of Succiso, that was damaged by acceleration of earth slide movements in 1951, 1952 and, quite severely, in 1966 and 1972. Succiso was first declared, according to law 445/1908, as “to be consolidated” (DPR n 201 of 14/02/1957) and, later on, as “to be transferred” (DL n°976 of 18/12/1966 – G.U. 24/4/70). From 1972 to 2008 the landslide did not underwent any other particular acceleration event and presumably, it moved at rates in the order of few cm/year, as it does presently. Consequently, the village of Succiso was again re-classified as “to be consolidated” (DGR n° 686 of 12/05/2008). Following such recent administrative act, and in order to define, design and construct consolidation works, the local technical basin service (Emilia Romagna Region) has undertaken an intensive geological, geotechnical investigation and monitoring survey
that allowed to define the geological model and the on-going kinematics of the landslide's deposit. This work supports feasibility analysis of a shield of deep drainage wells to be possibly located in the central portion of the landslide (indicatively: 26 wells, diameter 1 m, depth 30 m, inter-axes 7-8 m, total length of shield 200 m, gravity discharge).Specifically, it performs a forward simulation of groundwater level changes induced by this possible deep drainage solution, using an hydrogeological modeling of the landslide based on 3D FEFLOW software, which has been calibrated thank to a continuous piezometric monitoring. A parent paper presented at this conference has complemented the feasibility analysis by using the outputs of this hydrogeological simulation as input to a geotechnical softsoil-creep model, in order to analysing the potential benefits, in terms of decrease in displacement rates, induced by deep drainage wells
Appraise the structural mitigation of landslide risk via numerical modelling: a case study from the northern Apennines (Italy)
No full textThe Ca’ Lita landslide is a large and deep-seated mass movement located in the northern Apennines, about 70 km west of Bologna (Northern Italy). It consists of a composite landslide that affects Cretaceous to Eocene flysch rock masses and chaotic complexes. Many of the sectors making up the landslide have resumed activity between 2002 and 2006, threatening some villages and an important road connecting several key industrial facilities located in the upper watershed. This paper presents the management of the emergency, dealing with the investigation campaigns (geological, geomorphological and LiDAR surveys, borehole drillings, seismic surveys), with the monitoring (in situ instrumentation) and with the design and construction of mitigation measures. The whole process, from landslide reactivation to date, has been modelled on a numerical basis with the finite difference code FLAC 2D, to assess the efficiency of the mitigation system and to propose further countermeasure works in different scenarios
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